title: Visualising a viral RNA genome poised for release from its receptor complex.
abstract: We describe the cryo-electron microscopy structure of bacteriophage MS2 bound to its receptor, the bacterial F-pilus. The virus contacts the pilus at a capsid 5-fold vertex, thus locating the surface-accessible portion of the single copy of the pilin-binding maturation protein present in virions. This arrangement allows a 5-fold averaged map to be calculated, showing for the first time in any virus-receptor complex the nonuniform distribution of RNA within the capsid. Strikingly, at the vertex that contacts the pilus, a rod of density that may include contributions from both genome and maturation protein sits above a channel that goes through the capsid to the outside. This density is reminiscent of the DNA density observed in the exit channel of double-stranded DNA phages, suggesting that the RNA-maturation protein complex is poised to leave the capsid as the first step of the infection process.
authors.affiliation: Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Katerina
authors.initials: K
authors.lastname: Toropova
authors.forename: Peter G
authors.initials: PG
authors.lastname: Stockley
authors.forename: Neil A
authors.initials: NA
authors.lastname: Ranson
mesh_terms: D000818:Animals; D020285:Cryoelectron Microscopy; D016679:Genome, Viral; D017909:Levivirus / Q000502:physiology* / Q000648:ultrastructure*; D019251:Nucleocapsid / Q000737:chemistry / Q000648:ultrastructure; D012367:RNA, Viral / Q000737:chemistry* / Q000378:metabolism; D011991:Receptors, Virus / Q000737:chemistry* / Q000378:metabolism; D053586:Virus Internalization
chemical_list: D012367:RNA, Viral; D011991:Receptors, Virus